1. Field of the Invention
The present invention relates to a manual paper feed apparatus incorporated in an image forming apparatus such as an electrophotographic copying machine.
2. Description of the Prior Art
In an electrophotographic copying machine as a typical image forming apparatus, each cassette loaded in the apparatus stores a plurality of recording sheets of a different size. A document image is recorded on a recording sheet having a size selected by a user or a recording sheet which is automatically selected in accordance with a document size.
Another copying machine can record a document image on a recording sheet having a size different from the sizes of recording sheets stored in a cassette. In this copying machine, a recording sheet having a desired size can be manually inserted from a predetermined insertion port without exchanging cassettes, and a document image can be recorded on the inserted recording sheet. An apparatus used for such an operation is called a manual paper feed apparatus.
FIGS. 1 and 2 show a conventional known manual paper feed apparatus. FIG. 1 shows a state wherein a sheet of paper is fed from a cassette. FIG. 2 shows a state wherein a sheet of paper is manually fed.
Referring to FIGS. 1 and 2, reference numeral 1 denotes a pivotal paper feed plate; and 2, a paper-receiving plate designed to slide in a front-rear direction upon pivotal movement of the pivotal paper feed plate 1. When the pivotal paper feed plate 1 is pivoted up on a support shaft 3, a proximal hook portion 2a is locked by a lock portion 1a of the plate 1, and the paper-receiving plate 2 is moved backward, as shown in FIG. 1. When the pivotal paper feed plate 1 is pivoted down as shown in FIG. 2, the paper-receiving plate 2 is pushed by a press portion 1b and is moved forward. During this forward movement, the paper-receiving plate 2 and the pivotal paper feed plate 1 constitute a continuous inclined surface. Reference numeral 4 denotes a paper end regulating step with which the leading end of a manually-fed sheet 5 is brought into contact. When the paper-receiving plate 2 is moved forward, the step 4 is moved to a position under a manual feed pickup roller 6 (for paper to be manually fed).
Reference numeral 7 denotes a push-up plate for urging the manually-fed sheet 5 stacked on the paper-receiving plate 2 against the pickup roller 6 via a through hole 2b. During the forward movement of the paper-receiving plate 2, the push-up plate 7 protrudes from the upper surface of the plate 2 via the through hole 2b. During the backward movement of the paper-receiving plate 2, the push-up plate 7 retreats below the plate 2.
Reference numeral 8 denotes a paper feed cassette; 9, sheets of paper stacked in the cassette 8; 10, a cassette pickup roller (for paper to be fed from the cassette); 11, a push-up plate for urging the sheet 9 against the pickup roller 10; 12, a separating member which is brought into contact with the pickup roller 10 upon forward movement of the paper-receiving plate 2; 13, a slip piece which slips under the pickup roller 10; 14, a separating roller unit; and 15, a second pickup roller pair.
In the above-described arrangement, when the pivotal paper feed plate 1 is in a vertical position as shown in FIG. 1, the sheets 9 stacked in the paper feed cassette 8 are pushed up by the push-up plate 11 and are picked up by the pickup roller 10 which is in contact therewith. The sheets 9 are then separated by the separating roller unit 14, which is located at a front position, one by one so as to be fed to the second pickup roller pair 15.
When the pivotal paper feed plate 1 is pivoted down, and the paper-receiving plate 2 is moved forward as shown in FIG. 2, the separating member 12 is brought into contact with the pickup roller 10, and the slip piece 13 slips into a space below the pickup roller 10. With this movement, the pickup roller 10 is insulated from the sheets 9 stacked in the cassette. Therefore, if the manually-fed sheet 5 is set on the paper-receiving plate 2, the sheet 5 is picked up by the pickup roller 6. The sheet 5 is then preliminarily separated by the pickup roller 10 and the separating member 12, and is finally separated by the separating roller unit 14 so as to be fed to the second pickup roller pair 15.
In the above-described manual paper feed apparatus, however, the separating member 12 is formed by directly bonding a friction member (e.g., a rubber material) to the upper surface of the paper-receiving plate 2. Therefore, when the paper feed cassette 8 is loaded, a large push-up force is applied to the slip piece 13 by the push-up plate 11 as shown in FIG. 3. As a result, the separating member 12 is urged against the pickup roller 10 with excessive pressure (an arrow B), and manual paper feed may not be performed.